The present invention is directed towards a solution of the problem heretofore present in coin operated locker cabinets involving the prevention of unauthorized opening of the locked doors of the cabinet by the expedient of gaining access to their associated coin operated lock units.
In typical commercially available locker cabinets of the type generally described for instance in U.S. Pat. Nos. 3,193,074; 3,228,506 and 3,599,770, a lock unit is inserted through a forwardly opening recess provided in a lock unit mounting post and releasably retained in mounted condition within such mounting post by operation of a custodian lock. A drawback of this type of construction is that the lock unit can be pried from within the mounting post by means of a strong bar or the like to a degree sufficient to remove the lock bolt of the lock unit from locking engagement with its associated cabinet door and thereby afford unauthorized access to stored contents of the locker cabinet.
In a variation of the above construction, which is disclosed for instance in U.S. Pat. Nos. 2,675,107; 2,707,043 and 3,460,662, a security plate(s) is removably fixed to the front of a lock unit mounting post, such as to overlie and protect the individual lock units. However, the security plate is itself susceptible to unauthorized removal by a prying operation with the result that the lock units may be exposed for tampering.
An alternative approach, which is disclosed for instance in U.S. Pat. Nos. 2,723,018; 3,249,197; 3,397,765 and 3,450,244, involves the mounting of a lock unit within a housing fixed to the rear surface of each individual cabinet door. However, typical cabinet doors are provided with a front panel fabricated from relatively light gauge sheet steel or the like, which may be readily pierced to afford access to the lock unit, while the cabinet door is in its locked condition. Another problem with this type of installation is that, when the cabinet door is unlocked, ready access is provided to the housing of the lock unit, such as to permit prying thereof from the inside of the door. While of course, the thickness of the door front panels and the housings of the lock units may be substantially increased, the additional weight involved is undesirable, since it requires that the hinges of the doors be strengthened to carry the additional weight and results in the overall cost of the cabinet being greatly increased.